Fe3O4 Magnetic Fluid Research Articles

CMOS-compatible plasmonic magnetic field sensor: An alternative approach using ultra-compact MIM configuration

This paper introduces a novel magnetic field sensor (MFS) that utilizes a metal-insulator-metal (MIM) waveguide integrated with a resonator structure and incorporates water-based Fe3O4 magnetic fluid. The sensor uses titanium nitride (TiN) as the plasmonic material which offers numerous advantages over conventional noble plasmonic materials. The sensor takes advantage of the tunable optical properties of the magnetic fluid and TiN to detect changes in the external magnetic field and quantify the magnetic field strength which has been demonstrated using the Finite Element Method (FEM). Our proposed MFS exhibits a high sensitivity of 11.97 pm/Oe, a narrow-band full-width half maximum of 93.66 nm, and a resolution of 8.36 × 10−4 Oe. The sensor is also compatible with complementary metal oxide semiconductor (CMOS) fabrication techniques, which enables chip-scale integration and low-cost production. The sensor can be used for various applications in navigation, military, space, healthcare, and beyond.

Magnetic-fluid-infiltrated bilaterally polished photonic crystal fiber with butterfly core for LSPR based magnetic field sensing via water based Fe3O4 magnetic fluid

In this manuscript, a sensor is devised employing photonic crystal fiber with localized surface plasmon resonance (PCF-LSPR), emphasizing the manipulation of refractive index (RI) through magnetic fluid (MF). The sensor's air holes adopt a hexagonal arrangement, forming a butterfly core design, and the transmission channels for the effective confinement of optical field energy relies significantly on the regions surrounding the central air hole in both directions. MF serves as the sensing medium, and the top and bottom polished surfaces are coated with gold and titanium dioxide. The sensor undergoes analysis using the finite element method, scrutinizing its model characteristics, structural parameters, and sensing performance. The results indicate a wavelength sensitivity of up to 45,600 nm/RIU and a maximum figure of merit (FOM) of 434 RIU−1. Within the range of magnetic field 30–150 Oe, the highest magnetic field sensitivity records 3350 pm/Oe. Over the temperature range of 27.4–114 °C, the temperature sensitivity measures only 310 pm/°C. A maximum sensor resolution of 2.19×10−6RIU is achieved for x−pol. The linear relationship between the resonant wavelength and the magnetic field yields R2=0.9945, for degree (2) for x−pol. The proposed sensor exhibits notable advantages, including a structure which is very stable, high sensitivity, ease of integration, and resilience to electromagnetic interference. Additionally, it excels in detecting weak magnetic fields. Its potential applications span from industrial production, military technology, to medical equipment.

Preparation of water-based dextran-coated Fe3O4 magnetic fluid for magnetic hyperthermia

Abstract Fe3O4 nanoparticles were prepared by chemical co-precipitation, modified with dextran, and dispersed in water to form a magnetic fluid (MF) for use in biomedical areas. The analyses of stability and magnetic property demonstrate that the prepared functional MF possesses outstanding stability (stability index within 60 days, high dilution stability, and autoclaved stability) and high magnetization (the values χ and M s of MF are 5.87 × 10−4 and 20.57 emu/g, respectively). Due to the coating of dextran, the toxicity of MF is minimal (in vitro survival rate of MCF-7 cells, blood compatibility, and in vivo toxicity). In addition, although the outer layer is coated with dextran, the M s intensity remains high, so the Fe3O4 MF owns a fast magnetic temperature response (when the MF concentration is 55 mg/mL, it can rapidly rise to 55°C within 800 s), which plays an extremely vital role in MF hyperthermia. So, the MF can effectively cause necrosis of human lung A549 cells, which shows a certain application potential.

Preparation and Magnetic Manipulation of Fe3O4/Acrylic Resin Core-Shell Microspheres.

Core-shell microspheres refer to duo-layer or multilayer microspheres, which are widely used in drug delivery, microreactors, etc. Accurate manipulation of microspheres is a research hot spot, while traditional manipulation methods including ultrasonic manipulation and laser manipulation still face some limitations. In this study, magnetic core-shell microspheres were adopted to realize the accurate manipulation of microspheres. Combined with microfluidic technology, polystyrene sulfonic acid (PSSA)/Fe3O4 magnetic fluid was utilized as the core material and photosensitive acrylic resin became the shell material. After UV curing, a magnetic core-shell microsphere with an average size of 55 μm could be achieved, and the diameter was uniform and controllable. By adjusting the flow rate of the dispersed phase, the dual-core microspheres with different core particle sizes that ranged from 9.3 to 28.4 μm could be prepared. Experimental results showed that the prepared Fe3O4/acrylic resin core-shell microspheres can be used as functionalized microspheres that have good magnetic response properties and self-assembly ability. In addition, the magnetic manipulation and self-assembly of the prepared core-shell microspheres were presented with different external magnetic fields. The magnetic core-shell microspheres have shown great potential in the fields of biomedical engineering and targeted delivery of drugs.

Viscoelastic and microwave resonant absorption studies of NixFe3−xO4 (0 ≤ x ≤ 0.7) mixed ferrite nanoparticle based magnetic fluid

We investigated the effect of Ni substitution on oleic acid coated Fe3O4 magnetic nanoparticles of 10–13 nm size dispersed in kerosene medium with enhanced colloidal stability. Study of molecular dynamics and coating of oleic acid to ferrite NixFe3−xO4 (0 ≤ x ≤ 0.7) nanoparticles was confirmed by Fourier transform infrared spectroscopy (FTIR) measurements. The increase of Zeta potential (ζ) up on Ni concentration confirms the stability of Ni substituted Fe3O4 magnetic nano fluid. Magnetization measurements (M-vs-H) reveals the substitution of Ni2+ suppresses the magnetic moment thereby decrease of saturation magnetization while increase in Ni concentration from x = 0–0.7 of Fe3O4 nano magnetic fluid. Moreover, field dependent elastic (G′) and viscous (G′′) modulus recorded at varying strain rate confirms a cross-over from viscoelastic-to-viscous behavior of Ni substituted Fe3O4 nanofluid. Further, the induced spin-disorder upon Ni concentration in corroboration with microwave resonant absorption (EPR) measurements through the increase of resonance field and narrowing of peak-to-peak linewidth indicating the suppression of magnetic dipole interactions and enhancement of super-exchange-interactions (Fe3+-O-Ni2+/Fe2+-O-Ni2+) . Moreover, the dominance of spin-spin interactions over the spin-lattice interactions was determined by EPR relaxation-time-scales: spin-spin relaxation (τ2) increases and spin-lattice relaxation (τ1) decreases, which is in conjunction with lande-g-factor while increasing Ni concentration. The present results are useful for knowing the effect of Ni concentration on magnetic and viscoelastic properties of NixFe3−xO4 (0 ≤ x ≤ 0.7) magnetic nanoparticles. Also, it offers a chance to create such types of stable nano magnetic fluids that may be actively controlled by outside magnetic fields, which results in heat sink damping materials in sealed devices and biomedical applications, etc.

Investigation of the surface tension of water-based Fe3O4 magnetic fluids under magnetic field: The effect of surfactants

In this work, water-based Fe3O4 magnetic fluids were prepared and the effect of surfactants on magnetic surface tension was investigated under a constant magnetic field. Different surfactants include anionic surfactants citric acid and sodium dodecyl sulfate (SDS); nonionic surfactants polyvinyl pyrrolidone (PVP K30) and polyethylene glycol(PEG-600) were employed to modify Fe3O4 nanoparticles. After the modification, the stability of Fe3O4-SDS magnetic fluid improved greatly, with the zeta potential improved to −40.5 mV compared to Fe3O4 magnetic fluid (−22 mV) without surfactants. X-ray diffraction and Fourier transform infrared spectroscopy were employed to characterize the crystalline and the surface changes. The results showed that the surfactant was successfully coated on the surface of Fe3O4 without changing the crystallinity. The surface coverage of nanoparticles by the surfactants caused a smaller saturation magnetization than uncoated Fe3O4 nanoparticles while keeping the superparamagnetic behavior. More importantly, the surface tension of the magnetic fluid was measured by the Du Noüy ring method, and an in-depth study of the magnetization time and direction on the magnetic surface tension has been carried out. Visual characterization of the cluster structure was carried out for an in-depth analysis of the influence of the external magnetic field on magnetic surface tension.

Preparation and Performance Research of Magnetic Polymer Microspheres

In this thesis, polystyrene magnetic polymer microspheres with good monodispersity and carboxyl functional groups were prepared. The adsorption properties of styrene-acrylic acid magnetic polymer microspheres to bovine serum albumin have been studied.. Using Fe3O4 magnetic fluid as the magnetic core and styrene-acrylic acid copolymer as the polymer shell, composite microspheres with very small particle diameters were prepared by the dispersion polymerization method.

Magnetic biochar particles prepared by ion cross-linking to remove phosphate from water

In this study, the ionic cross-linking method was used to synchronize the granulation and magnetization of biochar powder. A precursor of Ca/Mg modified, tobacco stalk biochar combined with sodium alginate as the functional monomer, CaCl2 solution as the cross-linking agent, and a Fe3O4 magnetic fluid dopant were used to prepare magnetic biochar particles (EMCSB3), which were easy to separate and recover. The adsorption performance of phosphate by these EMCSB3 was explored. The Langmuir model fitted adsorption capacity of phosphate on the EMCSB3 was 8.93 mgP g−1, which was comparable to other materials at the same concentration. The process of phosphate adsorption by magnetic particles followed a pseudo-second-order model, and the adsorption mechanism was chemisorption. EMCSB3 was suitable for use in environments with pH ≤ 8, the best dosage was 6.67 g l−1, and its removal rate was maintained at about 85%. Phosphate adsorption was greatly affected by coexisting CO3 2−. This study provides a technical approach for the granulation and magnetization of powdered biochar and improves its feasibility of use.

Analysis of water conveying iron(iii)oxide nanoparticles subject to a stationary magnetic field and alternating magnetic field

Present physical models describe the effects of magnetic field-dependent viscosity on unsteady water-based Fe3O4 magnetic fluid flow over a rotating and vertical moving disk. The first model represents the effect of magnetic field-dependent viscosity in the presence of a stationary magnetic field and the second model demonstrates the presence of an alternating magnetic field. However, the previous investigation of water conveying iron(iii)oxide nanoparticles flow in a rotating system is not available on the comparison of spatially variable magnetic field and alternating magnetic field on the velocity distribution in the presence of rotating and vertical moving disk. The variations in the viscosity due to the alternating magnetic field depend not only on the strength of the magnetic field but also on the frequency of the alternating magnetic field. This study might have a significant role in the improvement of the sealing of rotating shaft and study of magnetic field dependent viscosity of water conveying iron(iii)oxide nanoparticles are important for hyperthermia in the treatment of cancer disease. An alternating magnetic field generates higher friction on the disk as compared to the stationary magnetic field.

Facile Way to Prepare a Porous Molecular Imprinting Lock for Specifically Recognizing Oxytetracyclin Based on Coordination.

Molecularly imprinted polymers (MIPs) are a kind of synthetic receptor-like materials. They have drawn more and more attention in the past decades. In this work, a facile method was developed to prepare porous magnetic MIPs utilizing metal coordination. The preparation is simply done using conventional oil-in-water emulsifier-free emulsion technology by mixing poly(styrene-co-itaconic acid), oxytetracyclin (OTC), Cu(II), and Fe3O4 magnetic fluid in one pot with a reaction time of 3 h. The product shows high specificity and selectivity toward OTC, as well as an excellent saturation adsorption capacity (62.567 mg/g). Emphasizing that the imprinting factor is 29, which is the highest one among the reported MIPs to the best of our knowledge. Combined with high-performance liquid chromatography, it was used successfully to determine OTC in pork liver, one of the most complex bio-samples. Recoveries are higher than 91.0% with relative standard deviations less than 4.5% at three spiked levels (n = 3). All evidence testifies that the MIPs based on metal coordination show excellent recognition selectivity and specificity, as well as large rebinding capacity. The strategy holds promise as a reliable, extensible, and versatile way for preparing a metal ion-mediated molecular-imprinting polymer.

Study on the Fluidity Experiments of Engine Oil-Based Magnetic Fluid with Fe3O4/Ag Nanoparticles

In this research, a new engine oil-based Fe3O4/Ag magnetic fluid is prepared applying the method of modified chemical co-precipitation. This preparation method is green without toxic gases being released. The nanoparticles are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and vibration sample magnetometer (VSM). These characterizations demonstrate that the Fe3O4/Ag nanoparticles modified by oleic acid are successfully synthesized and uniformly dispersed in the engine oil. The hysteresis loop of this new magnetic fluid shows that it has no remnant magnetism and maintains superparamagnetic properties. Shear stress and viscosity of both Fe3O4magnetic fluid and Fe3O4/Ag magnetic fluid are measured by the rotational rheometer. The shear stress increases with the increasing shear rate while the viscosity decreases with the increasing shear rate. What’s more, the viscosity of Fe3O4/Ag magnetic fluid significantly increases compared with the traditional magnetic fluid.

Application of Amorphous Nanoparticle Fe-B Magnetic Fluid in Wastewater Treatment

Amorphous magnetic particles demonstrate excellent comprehensive properties and outstanding characteristics for numerous applications. In this report, magnetic crystalline Fe3O4 and amorphous Fe-B nanoparticles were successfully synthesized and introduced to prepare water-based magnetic fluids. The Fe3O4 and Fe-B particles are homogeneous nanoparticles with an average particle size of [Formula: see text][Formula: see text]nm. The shape of Fe-B amorphous nanoparticles is regular. The saturation magnetizations of Fe-B and Fe3O4 particles are 74 emu/g and 69 emu/g. The use of crystalline Fe3O4 magnetic fluid and amorphous Fe-B magnetic fluid in advanced treatment of high concentration organic wastewater was presented. The removal rate of chemical oxygen demand by using the amorphous Fe-B magnetic fluid reached 96%, about 16% higher than that by using the Fe3O4 magnetic fluid. Moreover, compared with Fe3O4 magnetic fluid, the treatment results demonstrate that the decolorizing effect by using the amorphous Fe-B magnetic fluid was 20% higher. It has been found that the nano-size Fe-B particles in magnetic fluid with amorphous structure led to high efficiency of wastewater treatment due to the catalytic activity.

Dynamic magneto-optical inversion in magnetic fluid using NanoMOKE

Abstract Systematic inversion of optical anisotropy with magnetic field sweep (0–5000 Gauss) has been observed at a critical concentration in the monodispersed magnetic fluids using NanoMOKE III. This experimental technique is significantly novel method to investigate the optical anisotropy of magnetic nano-suspensions with the time-varying magnetic field. In this work, we report a detailed experimental investigation on the field dependent magneto-optical behaviour of dilute water dispersed Fe3O4 based magnetic fluid. Magnetic fluid shows tunable magneto-optical properties which primarily depends on parameters such as, particle concentration, composition and carrier medium. We have observed a systematic inversion in optical anisotropy at critical concentration for a Fe3O4 magnetic fluid with strong spatial dependence. The observed tuneable magneto-optical phenomena have been correlated to the net effect of the structuration process, electronic transitions and gravitational force in the presence magnetic field. This phenomenon leads to the development of two particle size distribution, negative optical activity initially and strong spatial dependence respectively. The present results provide a strong correlation with theoretical models presented to expound the dependency of various parameters on magneto-optical inversion behaviour of magnetic fluids.

Recyclable Magnetic Titania Nanocomposite from Ilmenite with Enhanced Photocatalytic Activity.

Using ilmenite as a raw material, iron was converted into Fe3O4 magnetic fluid, which further was combined with titanium filtrate by a solvothermal method. Finally Fe3O4/TiO2 nanocomposites with the uniform size of 100–200 nm were prepared. This approach uses rich, inexpensive ilmenite as a titanium and iron source, which effectively reduces the production cost. The crystal structure, chemical properties and morphologies of the products were characterized by SEM, TEM, XRD, FTIR, BET, UV-Vis, XPS and VSM. The novel photocatalyst composed of face-centered cubic Fe3O4 and body-centered tetragonal anatase–TiO2 exhibits a spherical shape with porous structures, superparamagnetic behavior and strong absorption in the visible light range. Using the degradation reaction of Rhodamine B (RhB) to evaluate the photocatalytic performance, the results suggest that Fe3O4/TiO2 nanocomposites exhibit excellent photocatalytic activities and stability under visible light and solar light. Moreover, the magnetic titania nanocomposites displayed good magnetic response and were recoverable over several cycles. Based on the trapping experiments, the main active species in the photocatalytic reaction were confirmed and the possible photocatalytic mechanism of RhB with magnetic titania was proposed. The enhanced photocatalytic activity and stability, combined with excellent magnetic recoverability, make the prepared nanocomposite a potential candidate in wastewater purification.

Optical Properties of Fe3O4 Magnetic Fluid from Iron Sand

Nowadays, a high sensitive sensor for the magnetic field has become an essential tool that vastly desired in several fields, especially in biomedical application. Therefore, the development of preparing material for the magnetic sensor becomes crucial to be conducted. In this experimnet, we propose the use of Fe3O4 magnetic fluid prepared from a local iron sand in Indonesia as a material for a magnetic sensor. In this work, optical activities of the Fe3O4 magnetic fluid as the effect of magneto-optics were performed under varying external magnetic field. The polarization direction change of the laser was detected as a function of the external magnetic field with the exponential function. Moreover, the intensity collected by a photodetector exhibited a linear correlation with the external magnetic field. These phenomena become strong evidence that the prepared Fe3O4 magnetic fluid opens potential to be applicated further as sensors, especially as a high sensitive optics-based sensor for the magnetic field.

Soft magnetic nanocomposite microgels by in-situ crosslinking of poly acrylic acid onto superparamagnetic magnetite nanoparticles and their applications for the removal of Pb(II) ion

FeCl3·6H2O and FeCl2·4H2O is used to produce a water-based nanometer Fe3O4 magnetic fluid, which is in-situ modified in liquid paraffin with silane in the form of water-in-oil emulsion. The emulsion of the resulting multi-functionalized Fe3O4 magnetite nanoparticles is then used as the only crosslinker and in-situ grafted with acrylic acid to produce beaklike soft magnetic nanocomposites microgels. This “one-pot” process has a number of advantages over the traditional methods: it is a simpler process; it avoids aggregation of nanometer Fe3O4; and it shows a much improved mechanical strength credited to the covalent crosslinking between the rigid Fe3O4 skeleton and the soft PAA blocks. The obtained microgels have showed selective adsorption to Pb(II), and the adsorbed Pb(II) can be easily desorbed, suggesting good reusability. Also, the microgels exhibit certain magnetic properties, therefore providing a convenient approach for stirring or separation by applying external magnetic field.

Ultrasensitive magnetic field sensor based on an in-fiber Mach–Zehnder interferometer with a magnetic fluid component

An ultrasensitive magnetic field sensor based on a compact in-fiber Mach–Zehnder interferometer (MZI) created in twin-core fiber (TCF) is proposed, and its performance is experimentally demonstrated. A section of TCF was spliced between two sections of standard single-mode fibers, and then a microchannel was drilled through one core of the TCF by means of femtosecond laser micromachining. The TCF with one microchannel was then immersed in a water-based Fe3O4 magnetic fluid (MF), forming a direct component of the light propagation path, and then sealed in a capillary tube, achieving a magnetic sensing element, which merges the advantages of an MZI with an MF. Experiments were conducted to investigate the magnetic response of the proposed sensor. The developed magnetic field sensor exhibits a linear response within a measurement range from 5 to 9.5 mT and an ultrahigh sensitivity of 20.8 nm/mT, which, to our best knowledge, is 2 orders of magnitude greater than other previously reported magnetic sensors. The proposed sensor is expected to offer significant potential for detecting weak magnetic fields.

Effects of γ-Fe2O3 on γ-Fe2O3/Fe3O4 composite magnetic fluid by low-temperature low-vacuum oxidation method

In this paper, the controllable γ-Fe2O3/Fe3O4 composite nanoparticles were prepared by low-temperature low-vacuum oxidation of Fe3O4 directly in different time. The Fe3O4 nanoparticles were synthesized by chemical co-precipitation, and they were almost spherical particles and had no significant changes during the thermal oxidation. The prepared samples were identified by X-ray powder diffraction (XRD), Raman spectra (RS), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The γ-Fe2O3/Fe3O4 was obtained by Fe3O4 oxidized from 0 to 24h, pure γ-Fe2O3 was obtained by Fe3O4 oxidized 24h and its saturation magnetization was 55.86emu/g. The magnetic nanoparticles were evenly dispersed in the silicone oil under the help of oleic acid and emulsifier, the Fe3O4, γ-Fe2O3/Fe3O4 and γ-Fe2O3 magnetic fluid with same viscosity were prepared. In the initial stage of thermal oxidation, the saturation magnetization of magnetic fluid increased with the oxidation time increasing, with the thermal oxidation going on, the saturation magnetization of γ-Fe2O3/Fe3O4 magnetic fluid kept growth until it reaches the maximum critical value and the corresponding oxidation time was 16h, and then it began to decrease. And the maximum saturation magnetization of prepared γ-Fe2O3/Fe3O4 magnetic fluid was 25.08emu/g, which was much higher than that of Fe3O4 magnetic fluid (12.45emu/g) and γ-Fe2O3 magnetic fluid (14.25emu/g).

Preparation and characterization of silicone-oil-based γ-Fe2O3 magnetic fluid

In this study, silicone-oil-based γ-Fe2O3 magnetic fluid was successfully prepared by thermal oxidizing of Fe3O4 magnetic nanoparticles, which were prepared by chemical co-precipitation with FeSO4·7H2O and FeCl3·6H2O, and their surface was modified by oleate ligands. Silicone oil was used as carrier liquid and oleic acid was as surfactant for preparing γ-Fe2O3 magnetic fluid. It is found that the Fe3O4 nanoparticles surrounded by oleate ligands are not damaged during the thermal oxidizing. The shape of γ-Fe2O3 magnetic nanoparticles prepared is similar to spherical, and their mean size is about 10–20 nm, which has nothing obvious difference compared with Fe3O4. The saturation magnetization of γ-Fe2O3 magnetic fluid prepared is 14.25 A·m2·kg−1 and that of γ-Fe2O3 nanoparticles is 57.56 A·m2·kg−1. The needle of γ-Fe2O3 magnetic fluid is much bigger than that of Fe3O4 magnetic fluid under the same magnetic field, which shows better magnetic properties.

A Magnetic Sensor Based on a Hybrid Long-Period Fiber Grating and a Magnetic Fluid

A magnetic sensor based on a hybrid long-period fiber grating (HLPFG) and an ester-based Fe3O4 magnetic fluid (MF) has been proposed and experimentally investigated. The Fe3O4 MF and HLPFG are encapsulated in a capillary tube using paraffin. The sensor is sensitive to a vertical magnetic field and environmental temperature, while it is not very sensitive to an axial magnetic field. Due to the hybrid structure of HLPFG, the transmission spectrum of the sensor has two groups of resonance dips that have different sensitivities to vertical magnetic field intensity and temperature. This sensor can be used for the simultaneous measurement of temperature and vertical magnetic field intensity, which is desirable to resolve the temperature cross sensitivity issue. The sensor is also advantageous in its ease of fabrication, compactness, and wide linear measurement range.